1. Technical Field
The present invention relates to an electronic system, and more particularly, to a substrate having a power plane and a ground plane and an electronic system having the substrate.
2. Discussion of the Related Art
Parts of an electronic device or system may be assembled using a structure that includes conductive elements such as traces, terminals, vias, and the like. For example, the structure may be a planar structure such as a substrate or a printed circuit board (PCB).
For example, in a computer system, microprocessors and memory modules are coupled to a PCB such as a mother board. Because the microprocessors and the memory modules are electrically coupled to each other through the conductive elements (e.g., traces, terminals, and vias), the microprocessors and the memory modules can communicate with each other. The memory modules may each include a plurality of semiconductor device packages mounted on a PCB. This PCB allows the semiconductor device packages to communicate with each other.
A substrate having a planar structure may include conductive layers that are separated from each other by a dielectric substance. Some of the conductive layers may have conductive traces that run parallel with a surface of the substrate. The conductive traces may be formed on different layers. The conductive traces may be electrically coupled to each other through conductive vias that are perpendicular to a surface of the substrate. Generally, the substrate may include at least one power plane that provides a power voltage and at least one ground plane that provides a ground voltage.
A power transmission system can affect the performance of a high speed electronic system. Propagating waves may result when some of the semiconductor device packages in the memory modules perform simultaneous switching operations. The propagating waves may induce a drop in a power voltage that is applied to the semiconductor device packages that do not perform the switching operations. The propagating waves are sometimes referred to as simultaneous switching noise (SSN).
The power plane and/or the ground plane may operate as a waveguide or a transmission line with relation to a signal line. When the power plane and/or the ground plane operates as the waveguide or the transmission line, noise generated in the power plane and/or the ground plane may degrade a quality of a signal transferred through the signal line.
To suppress the noise generated in the power plane and/or the ground plane, and thus, prevent the degradation of signal quality, a capacitor can be added between the power plane and the ground plane, or the power plane and the ground plane can be made to have an electric band gap (EBG) structure.
However, the addition of the capacitor between the power plane and the ground plane may fail to suppress the noise at high frequencies because of a parasitic inductance of the capacitor. In addition, this technique may amplify the noise at frequencies, which cause a resonance between the capacitor and inductors that are placed between the power plane and the ground plane. The use of the power plane and the ground plane that have the EBG structure may fail to suppress the noise at low frequencies and may be expensive to manufacture.
Accordingly, there exists a need for a substrate with a structure that is capable of preventing quality degradation of a signal transferred through a signal line.